Control of solution input to continuous centrifugal



Feb.24,1970' QRST'EELEETAL 3,497,385

CONTROL OF SOLUTION INPUT TO CONTINUOUS CENTRIFUGAL Original Filed Oct. 9, 1961 I I I I I I VENT 6 208' J INVENTORS.

Clarence R. Steele Frank B. Price ATTORNEYS United States Patent 3,497,385 CONTROL OF SOLUTION INPUT TO CONTINUOUS CENTRIFUGAL Clarence R. Steele and Frank B. Price, Denver, Colo., assignors, by mesne assignments, to CF & I Engineers, Inc., Denver, Colo., a corporation of Colorado Original application Oct. 9, 1961, Ser. No. 143,892, new Patent No. 3,226,257, dated Dec. 28, 1965. Divided and this application May 17, 1965, Ser. No. 456,439 Int. Cl. B04b 13/00 US. Cl. 12719 8 Claims ABSTRACT OF THE DISCLOSURE Automatic control of solution input to a continuous centrifugal having a valve-controlled inlet to the centrifugal basket and a motor for rotating the basket, means for sensing the load on the motor, pneumatic actuating means for the inlet valve, a first electric circuit responsive to said sensing means for changing the setting of the inlet valve, and a second electric circuit responsive to the motor operation for shutting said inlet valve when the motor is not running in loaded driving relation to the basket.

This is a division of application Ser. No. 143,892, filed Oct. 9, 1961, now US. Patent No. 3,226,257.

The present invention relates to apparatus for continuous centrifugal treatment of massecuite and similar solutions. Massecuite is defined as a dense mass of sugar crystals mixed with mother liquor and usually obtained by evaporation. More particularly, the present invention relates to control for the feed of massecuite or like solidscontaining solutions to a continuous centrifugal.

It is conventional to subject massecuite to separations in which the sugar crystals are recovered as a substantially dry product and the mother liquor, or molasses, is separately collected as a secondary product. One such treatment has been batch-centrifuging. Another treatment has entailed the use of continuous centrifugals, as they are termed in the art. Recent development work in the sugar industry on continuous centrifugals has been directed to overcoming the tendency of sugar crystals to fracture and break during initial introduction thereof to the machines. This occurs during the time interval required by the massecuite to attain the speed of the centrifugal basket. Until speed is attained excessive wear on the basket results.

One solution of the problem has been provided by continuous centrifugals which operate according to the thin layer principle; and in which massecuite feed material enters a first stage in which it is brought up to the speed of a centrifuge basket before passing to its screening area and thereafter moves as a thin layer or film across the screening surfaces of the basket in the actual centrifugal separation.

In the above identified parent application generally there is disclosed centrifugal apparatus including spaced inner and outer housings forming a chamber for centrifugal sugar or solution therebetween. A substantially frustoconical basket of particular construction is mounted for high speed rotation within the inner housing. A novel arrangement for separating liquids discharging from the basket and for mist control is provided. An inlet to the basket for solids-containing solution or viscous sugar solution is provided. Outlets are provided for conducting separated liquid fractions from the apparatus and for removing separated solids or sugar from the apparatus.

It is an object of our invention to provide a simple, efiicient and economical method for centrifuging massecuite and similar solids-containing solutions which eliminates excessive wear on the equipment used in practicing the process and which avoids crystal reduction in its liquids-solids separation.

A further object of the invention is to provide improved control for the feed to a continuous centrifugal.

The practice of this invention will be described with reference to the accompanying drawings. In the drawings, in the several views of which like parts bear similar reference numerals:

FIG. 1 is a side elevation view of centrifugal apparatus embodying this invention; and

FIG. 2 is a schematic diagram of a feed control system for continuous centrifugals according to this invention.

FIG. 1 illustrates the external arrangement of parts and appearance of the centrifugal, the interior structure of which is described in detail in the heretofore identified parent application, as well as the placement of lubricating fluid recirculating pump 181 and associated parts. A plurality of sugar sampling ports 154 are shown as spaced about the periphery of outer casing 130. The feed to inlet 137 is controlled by a butterfly valve regulating the outflow from a supply conduit 191. Butterfly valve 190 is mounted on a pivotal support rod 192 which extends across the diameter of inlet 137 for regulating the feed of solution through the inlet. Rotation of the butterfly valve is controlled by a dashpot or transducer 193 which contains a mechanical output connected to the valve and a flexible diaphragm (not shown) providing a pneumatic input. The diaphragm is actuated through pressure supplied through a line 194 which contains a three-way 440 v. solenoid operated valve 195 (FIG. 2). Valve 195 connects line 206 to line 194 when the motor is running and has its electrical coil portion which is connected in the motor power circuit deenergized to shut off its valve portion and thereby blocks flow from line 206 when the motor stops, thus permitting line 194 to bleed to atmosphere and stop the flow through the inlet as closed by the butterfly valve 190. This valve 190 is controlled through a transcope controller 196, which in turn is actuated by current transducer 197 interconnected with a current transformer connected in the power line of the centrifugal motor 198 thus establishing a predetermined opening through the inlet 137 for normal operation when the motor 198 is under full load. The current transformer measures the line current drawn by motor 198. Air supply is furnished through conduit 199, filter 200, valve 201 and line 202 to transcope controller 196 and current transducer 197. Line 202 is normally under 20 p.s.i. pressure.

When the centrifugal motor is actuated, the current transducer, which is wired thereto, is adapted to actuate the transcope controller to allow passage of air through solenoid operated valve 195 (which is likewise wired into the motor circuit) to provide pressure on the diaphragm of dashpot or transducer 193 and thereby open butterfly valve 190. In operation, current transducer 197 causes a zero to 15 p.s.i. pressure through line 205 and in cooperation with transcope controller 196 exerts a pressure through line 206 on the diaphragm of dashpot or transducer 193. Suitable gauges 207 and 208 are included in lines 202 and 206, respectively. A valve 211 allows for selective control of the pressure exerted by the transcope controller on dashpot or transducer 193, and gauge 210 indicates such control.

Thus the foregoing combines a simple control for both the feed and operation of a continuous centrifugal. The control system may be located at a remote location and is easily operated therefrom without operator supervision of the centrifugal. This control system has been discussed with reference to both embodiments of centrifugal apparatus described in the heretofore mentioned parent application.

Changes and modifications in the combination, arrangement and functioning of parts may be availed of within the spirit and scope of the invention as defined in the hereunto appended claims.

We claim:

1. In a continuous centrifugal apparatus having spaced inner and outer housings forming a chamber for centrifuged sugar therebetween, a substantially frustoconical centrifuge basket mounted for high speed rotation within the inner housing, an inlet for viscous sugar solution to be treated, a peripheral discharge passage from the basket to the centrifuged sugar chamber, outlet means for separating and conducting a separated liquid fraction from the centrifugal apparatus, additional outlet means for removing separated sugar from the centrifugal apparatus, a motor for rotating the basket, the improve ment which comprises valve means in the inlet for establishing a predetermined opening through the inlet when the motor is running in normal loaded driving relation to the basket, sensing means in the motor circuit, pneumatic actuating means having an air flow input line and a mechanical movement output operatively associated with said valve means, a first electric circuit coupled to said pneumatic actuating means in the input line and coupled to said sensing means for changing the setting of the valve means in response to a measured variation in the load on the motor, and a second electric circuit coupled to said pneumatic actuating means in the input line and coupled to said sensing means for shutting off said valve means when the motor is not running in a normal loaded driving relation to the basket.

2. In apparatus as defined in claim 1, in which the sensing means senses line current of the motor and converts said current to a proportional pressure output.

3. In apparatus as defined in claim 1, means for continuously measuring variations in the load on the motor and said first electric circuit being coupled with said actuating means for changing the setting of the valve means in response to each measured variation in the load on the motor.

4. In apparatus as defined in claim 1, wherein the line current of the motor is measured for measuring variations in the load on the motor.

5. In apparatus as defined in claim 1, wherein the actuating means includes a current transformer in the motor line, and an electrical to pneumatic transducer for changing the electrical measurements to a proportional pneumatic output.

6. In apparatus as defined in claim 1, wherein the actuating means includes a transducer having a pressure sensitive diaphragm with an air inlet controlled by the actuating means, and a mechanical output connected to said valve means.

7. In apparatus as defined in claim 1, wherein said sensing means is arranged for sensing when the motor stops and the actuating means shuts off the valve means in response to the sensing of the motor stoppage.

8. In apparatus as defined in claim 1, wherein said sensing means includes a solenoid operated valve with a coil portion connected to a power circuit of the motor and a valve portion controlling said actuating means.

References Cited UNITED STATES PATENTS 1,847,159 3/1932 Adams 2l0145 X 2,868,381 1/1959 Siegrist 210-143 3,322,277 5/1967 Pearson et al. 210-86 X OTHER REFERENCES Antriebe Fiir Volla'uto Matische Zentrifugen H. Hinz Zucker 13, pp. 535-539 (1960). Fiillmassezulaufregezung M. Brunke, Zucker 18, pp. 297-299 (1965).

Chemical Engineers Handbook Perry 4th Ed., pp. 22-80, 22-82 (1963).

MORRIS O. WOLK, Primary Examiner D. G. CONLIN, Assistant Examiner US. Cl. X.R. 

